Pneumatic component for a control bearing

ABSTRACT

An active pneumatic component for pneumatically controlling a hydraulic bearing includes an electrically driven oscillating membrane pump combined with a multiway valve into an integrated structural component, in such a way that an armature which activates the oscillating membrane also controls the valve functions of the multiway valve. The valve also containing the inlet and outlet valves of the pump.

[0001] The invention relates to a pneumatic component and particularly relates to an active pneumatic component.

[0002] The invention especially relates to a minimized combined component consisting of an oscillating membrane pump and a valve head having an inlet and an outlet and being switchable between different control states.

[0003] In particular, the invention relates to a pneumatic component for switching pneumatically switchable hydraulic bearings. Such bearings are well known in the field of automotive engineering.

[0004] Such a pneumatically switchable hydraulic bearing is known for example from the published German patent application DE 32 10 731 A1 disclosing a pneumatic pressure chamber defined in a cup-shaped chassis-connection fitting underneath a compensating diaphragm of a basically conventional hydraulic bearing. In the pressure chamber a variable pneumatic overpressure can be generated as a setting pressure directly influencing the stiffness of the hydraulic bearing by acting on the compensating diaphragm. According to the state of the art this pneumatic setting pressure is either externally generated and externally controlled or only externally generated and internally controlled with respect to the casing of the hydraulic bearing. This internal controlling of the pneumatic setting pressure is effected by the compensating diaphragm itself, which opens and closes a relief valve according to the deformation caused by the damping fluid located in the working chamber of the hydraulic bearing. The compensating diaphragm rolls up and down pushing a tappet of the valve to open the valve to a pneumatic pressure generator supplying constant pressure or releasing the tappet to close the valve by the restoring force of a spring. Therefore, according to the state of the art, an independent adjustment and switching of the hydraulic bearing can only be effected by a pneumatic pressure generator regulated by a real-time controller which are both located outside the component of the hydraulic bearing. This can obviously be attributed to the large size of these components which are dimensioned in accordance with the large pneumatic volumina to be moved.

[0005] According to the state of the art it is an object of the invention to provide an active pneumatic component comprising two functional components, namely pressure generation and pressure controlling that is at the same time small enough to be integrated in the casing of a conventionally dimensioned hydraulic bearing. This technical problem is solved according to the invention by a pneumatic component comprising the features of claim 1.

[0006] The dependent claims disclose embodiments of the invention.

[0007] The essential advantage which can be achieved with the component according to the invention is related to its simple and compact configuration. Due to the direct integration of the 3/2-port multiway valve in the oscillating membrane pump forming its top and accordingly due to the control of the valve operation by the pump and by means of the pump not only a miniature construction is achieved, but also not more than two lines of low voltage are required to control the switching states of the 3/2-port multiway valve as well as the states of the pump. This allows the direct integration of the pneumatic switching elements in the casing of the hydraulic bearing to be switched.

[0008] In the following, embodiments of the invention are described with respect to the unique figure of the drawings, wherein

[0009]FIG. 1 shows a pneumatic component comprising the features of the invention in an axial section.

[0010] In a casing 1 a 3/2-port multiway valve 2 and an oscillating membrane pump 3 are combined to a structural and functional unit. The multi-way valve 2 comprises an inlet 4 and an outlet 5. The inlet 4 is connected with an inlet channel 6 having an inlet valve 7.

[0011] Furthermore, the inlet 4 communicates with the outlet 5 of the component via a ventilation conduit 8 comprising a membrane valve 9 being closed by a biased spring 10.

[0012] Furthermore, the outlet 5 of the component is connected with an outlet channel 11 comprising an outlet valve 12. The outlet channel 11 is closed by the restoring force of a spring. The inlet channel 6 and the outlet channel 11 open into a pumping working chamber 13 of the oscillating membrane pump 3. On its opposite side the pumping chamber 13 is bounded by the oscillating membrane 14. The oscillating membrane 14 is driven by a plunger-type armature 15 of a reciprocating solenoid valve comprising a coil 16. The plunger-type armature 15 provides a drum-shaped cylindrical reinforcement 17 in central position of its axial extension. In a currentless or deenergized state of the magnetic coil 16 the cylindrical reinforcement 17 is supported in a defined rest position 20 by the restoring force of two restoring springs 18, 19.

[0013] When the coil 16 is energized by a constant current flow the cylinder 17 is lifted with respect to its axial center and supported in position 21 which corresponds to the maximal lifting 22 of the pumping membrane 14. In this position the membrane 14 opens the membrane valve 9 by shifting the tappet 23 extending into the pump chamber 13. The membrane valve is otherwise kept closed by the restoring force of a biased spring 10.

[0014] In case of a pulsating current flow having a rectangular pulse frequency the cylinder 17 and accordingly the armature reciprocally move back and forth. The amplitude of this oscillation is equal to the distance between the axial positions 20 and 24 with respect to the axial center of the cylinder 17. Thus the oscillating membrane 14 is lifted in the position indicated in FIG. 1 with broken lines. In this position it is just not in contact with the base 26 of the tappet 23 so that the relief valve 9 is closed. This is the normal operational state of the oscillating membrane pump 3. Furthermore a pneumatic overpressure is generated and available at the outlet fitting 5. 

1. An active pneumatic component especially for pneumatically switching of a hydraulic bearing, characterized by a combination of an electrically driven oscillating membrane pump (3) and of a multiway valve (2) to an integrated component in such a way that an armature (15, 17) which activates the oscillating membrane (14) also controls the function of the multiway valve.
 2. Component according to claim 1, characterized by an inlet (4) which opens to the ambient atmosphere and an outlet (5) which is switchable between one of the three switching states OPEN, CLOSED and PRESSURIZED.
 3. Component according to one of the claims I or 2, characterized by a pumping chamber (13) provided in front of the pumping membrane (14) into which an inlet channel (6) and an outlet channel (11) open; a base (26) of a tappet (23) also extending into the pumping chamber (13) due to the restoring force of a pullback spring (10); a top of said tappet opening a relief valve (9) of the multi-way valve (2) located in the pumping chamber by pressing the base of the tappet (26) out of the pumping chamber (13) connecting the inlet (4) of the component (1) with its outlet (5); said base of the tappet (26) being pressed out of the pumping chamber (13) by the pumping membrane (14) or a dome-type impact portion formed on the pumping membrane especially for this purpose, whereby the pumping diaphragm is in a position which corresponds to the maximum stroke (22) of the pumping diaphragm.
 4. Component according to one of the claims 1-3, characterized by an upper stationary point of stroke (25) of the oscillating membrane (14) which under normal pump conditions is positioned underneath the lowest stopping surface of the base of the tappet (26) with respect to the direction of the operational stroke of the pump.
 5. Component according to one of the claims 1-4, characterized by a rest position of the deenergized pumping diaphragm (14) which is positively adjusted due to the restoring force of restoring springs (18, 19) and which corresponds to the lower stationary point of the stroke (20) of the oscillating membrane (14) whereby, when the pumping diaphragm is in its rest position, the outlet valve (12) disposed in the outlet channel (11) of the pumping chamber (13) is closed and therefore the outlet (5) of the component (1) is shut off.
 6. Component according to one of the claims 1-5, characterized by an electromagnetic driver activating the oscillating membrane (14) providing a piston like reinforcement at a plunger-type armature (15) in its axially central position, wherein said armature is supported in a currentless state of the magnetic coil (16) underneath the center of the coil and therefore in a position corresponding to the lower stationary point (20) of the stroke of the diaphragm by the restoring force of restoring springs (18, 19) acting on both sides of said piston (17) and which by energizing the coil with a constant current flow is shifted against the force of the restoring springs (18, 19) in a position (21, 22) corresponding to the maximum stroke of the piston to be stationary supported in this position and which in case of energizing the coil with direct current flow having rectangular pulses reciprocates in axial direction corresponding to the normal stroke of the oscillating membrane activating the membrane whereby the width of the rectangular pulses is chosen to be smaller than the width required to lift the diaphragm to its maximum stroke and the distance of the supplied rectangular pulses is chosen to correspond with the time of turning back of the diaphragm (14) to the lower stationary point (20) of the stroke.
 7. Use of the pneumatic component comprising features of one or more of the claims 1-6 for pneumatically switching of hydraulic bearings in motor vehicles, said bearings comprising a loose piece for uncoupling vibrations and a control chamber having a displaceable wall which is formed by the loose piece. 